rust/src/test/run-pass/borrowck-preserve-box-in-uniq.rs

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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// exec-env:RUST_POISON_ON_FREE=1
fn borrow(x: &int, f: fn(x: &int)) {
let before = *x;
f(x);
let after = *x;
assert before == after;
}
struct F { f: ~int }
pub fn main() {
let mut x = ~mut @F{f: ~3};
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do borrow(x.f) |b_x| {
assert *b_x == 3;
assert ptr::addr_of(&(*x.f)) == ptr::addr_of(&(*b_x));
*x = @F{f: ~4};
debug!("ptr::addr_of(*b_x) = %x", ptr::addr_of(&(*b_x)) as uint);
assert *b_x == 3;
assert ptr::addr_of(&(*x.f)) != ptr::addr_of(&(*b_x));
}
}